Secondary refrigeration system



June 28, 1960 R. A. MOORE sscommv REFRIGERATION SYSTEM Filed Jan. 25, 1957 a TR R E O Z 5 EM 3 5T E R R FA PL P O NORM 2 000 GOFO m: k I

N 0 w E 2 MV "v E A RNEY 2,942,434 Patented June .28 .1960

United States Patent V 2,942,434 SECONDARY REFRIGERATION SYSTEM Robert A. Moore, 325 Barton St. 12., Hamilton, Ontario, Canada Filed Jan. 25, 1957, Ser. No. 636,445

s Claims. (Cl. 62-1-2118) This invention 'relates to refrigeration.

The invention relates particularly to secondary refrigeration. 1

A secondary refrigeration system according to this invention is applicable to the two-temperature type refrigerator having its lower temperature compartment (or freezer) at the bottom of the cabinet. Also according to the invention,heat is removed from one compartment at one level and transmitted, through the medium of latent heat (evaporation and condensation) to another compartment at a lower temperature, whether at a higher or lower level. As is known, the trend in recent years has been to install the lower temperature compartment at the bottom and the (higher temperature). evaporator atthe top, but this does not permit of employing a gravity-typesecondary system. 1 v I An object of the invention is to use a secondary refrige'ration system inthe present-day type of two-temperature refrigerators having the lower temperature compartment at the bottom of the cabinet.

Another object of the invention is to make possible a separate control of the temperature the higher temperature compartment, independently of the temperature in the'lower temperature compartment.

Another object of the invention-is to make possible a more even temperature in bothhigh and low temperature compartments, irrespective of load conditions imposed on either.

Another object of the invention is to make possible the manufacture of a refrigerator attachment to be easily installed adjacent to freezers and thus providea" separate high temperature refrigerator for perishable foods that do not require freezing.

Another object of the invention is to make possible a remote installation of a refrigerator built into, say, a kitchen or decorative panelling, without the concern condensing unit, in which case" all that is required is to havethe'high-te'mperature evaporator connected by 'suitable thermal contact to a remote low-temperature freezer by means of one small insulated pipe.

for cooling a space 13 to any temperature above that of the compartment 12, but lower than the ambient temperature surrounding the cabinet 10. The evaporator 15 may be of any type suitable to the shape and construction of the cabinet, the evaporator shown comprising an ac- .cumulator 14 and a depending surface or surfaces 15 to which is attached tubing 16 opening into the accumulator at 17 and 18.

of electric connections to the unit, or aclosely connected i 2 Within the compartment 12is a condenser 20 one-end of which is connected to the evaporator, more particularly to the accumulator 14, by an insulated pipe 21.; 'lE-he other end of the condenser opens into the lower end- 0f a receiver 23. I Mounted on the lower end (bottom) of the receiver 23 is an electric heater 25, which as shown, is of the immersion type. The heater, if preferred, could be of any other suitable type, such as the contact type. i

The heater, as will be seen presently, serves to heat and vaporize liquid refrigerant in the receiver. j

Suitably mounted in close proximity to the heatet so as to be sensitive to theternperature of-the lower end of the receiver, is a bi-metallic or thermostatic switch 26, the switch being biased to tend to open (break the circuit) as the temperature rises, and being closed at a minimum selected temperature. The purpose of the bi-metallic'or thermostatic switch 26 is to act as a thermal protector'and should be so calibrated as to open only upon failure of the pressure switch 28 to properly function.

A pressure switch 28 is operatively'connected to the upper end of a container or bulb 34 asby-a capillary tube or conduit 30. The switch shown is of the type wherein the bridge 36 is actuated (raised, or lowered) as by expandable and contractable bellows 24, closed at the top but connected at the bottom to the tube 30, the bellows expanding upon an increase in the pressure of the liquid refrigerant in thereceiver and contracting upon a de crease of pressure. Preferably, the bellows are springloaded downwardly, asiby a-spring 33,,so thatexpansion of the bellows is yieldin'glyresisted by the spring.

The internal volume ofv the bulb 34 must be greater than the combined volume of the capillary tube,3 0 and the bellows 24. The pressure switch 28 maybe, iffound expedient, equipped with a manually operated push button 35 to hold the contacts closed. The bellows 24, capillary tube or line 30 and the bulb 34 will be charged with suiiicient quantity or volume .of a suitable refrigerant to fill the bellows 24 and capillary tube 30 with liquid in the bulb 34 under normal operating temperatures. The bulb 34 should be neared in a convenient panama as to be sensitiveto the. temperature change of heater 25.

The parts 24, 30 and 34 comprise a separately sealed unit,

that is to say a unit independent of the pressures exerted in the receiver 23.

The system of switches just-presently deseiibed contrels the cycle, as will be presently seen, and therefore controls the temperature of the food storage space. M

The quantity of refrigerant'used depends obviously on the size-of the evaporator, and the size of theevaporator in turn is determined by the space tobe refrigerated, that is, the foodstorage space. The length diametenof t, the pipe 2 1 dependon'the distance between the two .corndetermined by the volume of the refrigerant used in the I entire system, and the position of the receiver relatively to the wall of the compartment.

Asalready stated, the bi-metallic switch 26 is biased to closeposition and responds to a rise in temperature to V Y open and break the circuit to the heater 25. Accordingly,

the switch 26 is positioned in close heat-exchange relation with the heater and conveniently, is mounted ithi the compartment 12. a

receiver.

The pressureswitch 28 is so chosen (or calibrated) thatthe contacts will open when the bulb 34 reaches a predetermined temperature. The pressure switch may be located either inside or outside the freezer compartment 12,-b'ut within thelimits of the length of the capillary tube 30, and within those of the electrical wiring circuit as indicated in diagram on the drawing.

- -The choice (orcalibration) of the switches, as just previously stated, is such that when there is very little liquid refrigerant in the accumulator and in the evaporator tubes there is a reduction of flow of vapor from the evaporator to the receiver 23. I

With the reduction of flow of vapor from the evaporator the temperature of the receiver 23- and the liquid refrigerant therein lowers, thus at the same time lowering ;the temperature of the bulb 34. This lowering of the -temperature of the bulb 34 reduces the pressure on the bellows 24 through the capillary tube 30. This allows the spring 33 to overcome the pressure of the bellows and close the contacts. The bi-metallic switch 26 being closed, will allow the current to flow to the heater 25.

The heater vaporizes the liquid refrigerant immediately surrounding it, the vaporized refrigerant rises in the receiver to displace and force liquid refrigerant into the condenser coil 20. The increased pressure overcomes the pressure in the accumulator and also the force of gravity of the refrigerant in the pipe 21, forcing the liquid refrigerant in the receiver into the condenser 20' and the pipe 21.

When the liquid refrigerant has been about completely forced out of the receiverythe heater and receiver warm up rapidly, causing the bulb 34 to warm up and vaporize 'therefrigerant in it. This action increases the pressure on the bellows 24 through the capillary tube 30, and overcomes the pressure exerted by the spring 33, thereby causing the switch 28 finally to open and break the circuit to the heater.

The lowering of the temperature of the condenser and receiver, by removal of heat to the walls of the freezer compartment, reduces the pressure, and the flow of vapor is drawn into the condenser, through the pipe 21. The heat in the compartment 11 vaporizes the liquid refrigerant in the accumulator 14 and tubes 16. This vapor. carrying the latent heat of vaporization, enters the pipe 21 at the top of the accumulator. The vapor is drawn through the pipe 21 by the continual reduction in pressure I claim:

1. A secondary refrigeration system for a refrigerating compartment in which the refrigerant fluid has a boiling temperature below ambient and substantially equal to the refrigeration temperature desired, comprising a closed accumulator with evaporator coils mounted in said compartment and having suflicient. capacity for accommodating all of said refrigerant fluid in its liquid state, means forming a lower temperature primary refrigeration compartment for comestibles, a closed condensate receiver and condenser coil for said refrigerant fluid, mounted in said primary refrigeration compartment, a single unrestricted insulated pipe for fluid flow between said accumulator and said condenser coil, and a thermostatically controlled heat means in said primary compartment for heating said refrigerant in said receiver to cyclically return the condensed fluid through said pipe to said accumulator.

2. A secondary refrigeration system as defined in claim 1, said evaporator coils extending below said accumulator and having inlet openings in the bottom of the accumulator and outlet openings extending substantially to the top of the accumulator, the end of said pipe connected to the accumulator also extending substantially to the top thereof.

3. A secondary refrigeration system as defined in claim 2, the condenser coil being connected to the bottom of said receiver, and an electric heater in the bottom of said receiver having a control switch which is set to close in response to a predetermined minimum temperature in the receiver to vaporize a portion of the refrigerant therein suflicient to drive substantially all the liquid stage fluid from the receiver and the condenser coil, through the pipe into the accumulator for a cooling cycle therein.

4. A secondary refrigeration system as defined in claim 3, said control switch having a closing spring biased to compress a bellows, and a thermostatic fluid bulb in said receiver connected by a capillary tube with said bellows.

5. A secondary refrigeration system as defined in claim 4, said control switch and bellows being located outside said compartments, said lower refrigeration temperature compartment being below said refrigerating compartment, and a thermal protective switch in series with said control switch and located in close heat-exchange relation with said heater, for operation in the event of failure of the control switch to open in response to a maximum temperature in said receiver. References Cited in the file of this patent UNITED STATES PATENTS 653,171 Coleman July 3, 1900 1,492,153 Van Hise Apr. 29, 1924 1,926,286 'Kindermann Sept. 12, 1933 2,040,744 Hull May 12, 1936 2,229,445 Fenander Jan. 21, 1941 2,317,283 Lyng'er Apr. 20, 1943 2,319,522 Schweller May 18, 1943 OConnell Dec. 26, 1950 

